Quote:
Originally Posted by Delphinus
Running the float valve on the sump right off the RO/DI itself is generally not recommended. I burned through membrane after membrane doing this and when asked about it on the boards (here and others) the answer was that RO/DI's don't do well with constant on/off cycling - whereas a single long runtime is best.
I don't know how Mark is getting away with not wrecking his membranes that way ... more power to him for getting away with it - but for the record this is not really a recommendable approach. Use a reservoir in between at the very least.
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You can run a direct line if you want and really it's the only way to get a real ATO rather than a semi auto. With an electronic system you can program the intervals to avoid the short bursts although I'm not sure it's that important. I've always run mine, and others I've setup, to work purely on demand with a short delay caused by a 10 second reaction time on the float. No obvious issues have been a result and my membrane is over 5 years old and still working close to as good as new. I think maybe in extreme cases where large dynamic pressure changes occur rapidly (like a manual float opening and closing rapidly from water movement) could cause damage to an RO through possible cavitation or some other anomaly and perhaps better quality units work better that others. These systems are primarily made for drinking water applications which is means they are primarily used in short run time applications so they should in theory handle that but they are not designed for humidifiers, or at least not primarily.
These are some recomdations from a manufacturer to increase membrane life:
- Replace your sediment filter at least every 6 months or as determined by pressure drop test. This will prevent membrane fouling due to silt or sediment depositing on the membrane.
- Replace your carbon block filter at least once every 6 months or when chlorine breakthrough occurs. This will ensure good membrane life and protect the membrane from chlorine damage.
- Your Membrane should not be operated at lower than the recommended concentrate (waste) to permeate (output or purified) water ratios.
- Operating reverse osmosis systems on softened feed water greatly reduces the chances of membrane fouling.